1. Field of the Invention
The present invention relates to a vehicular navigational system for guiding a driver through an established path to a destination.
2. Description of Related Art
In prior art navigational systems of this kind, a road used to establish a path to a destination is taken as a link connecting nodes. If a path going from the starting place to the destination is established using this link, then the road is displayed on a road map in highlighted or thickened form, or verbal instructions are issued to indicate the direction of movement of the vehicle along the path. In this way, the path going to the destination is shown.
It is to be noted, however, that the driver does not always go through the established path. Rather, he or she might go through a favorite or more familiar road. This is now described in detail by referring to FIG. 22A, where the driver's house is indicated by "X". It is assumed that a road indicated by the solid arrowhead line is included in the path, and that another road indicated by the broken arrowhead line is outside the path. Both roads are close to the driver's house. Even if a location indicated by the circle and existing on the road closest to his house is established within the path to urge the user to go in the direction indicated by the solid arrowhead line, the driver might go through the road indicated by the broken arrowhead line. Referring next to FIG. 22B, even if the path is established to include a road indicated by the solid arrowhead line, the driver might go through a detour indicated by the broken arrowhead line. In this manner, with the prior art navigational system, it is impossible to establish a path which takes account of the driver's experiences, practice, and habit.